Method and material for preventing the tarnishing of silverware



-' thus forming the oxide, though it is not limited -to a cloth treated with. such a silver compound 30 l I be of any color and we have also made severalwesis .7 i v METHOD AND MATERIAL FOR PREVENTING q w-THE TARNIsHING-o smvERwARs 1 Y t I l 1 Kenneth HBarnard,West Newton, and Henry F.

' ,Kane,' Lawrence, Mass., assignors 'to Pacific' ills, Lawrence, Mass, a corporation of Massa- Patented June 11 t chusetts N0 Drawing. Application May ,17, 193s,

.Serial No. 671,596 B -Claims. (01. 23-441) This is an improvement on the method and material patented by Grinnell Jones of Cambridge, Mass, Patent No. 1,766,646, June 24, 1930; for pre-' venting the tarnishing of silverware.

The Jones patent described a fabric for protecting silverware from tarnish comprising a material I suitable for wrapping impregnated with finely divided silver, or a compound thereof, which would combine with the tarnishinggases in the atmosphere and'thereby protect the silver wrapped in the protecting material.

The I Jones patent particularly describes a wrapping material impregnated with silver oxide formed by treatinga cloth with silver nitrate and Q tion-which are described in the tfollowingi specification, 1 a a more or less, dissolved in a gallon of water. This 1 45 may :be done in' a padder in which the cloth is a squeeze roll to remove the excess of silver nitrate.

precipitating the silver withsodium carbonate so formed. Many protecting cloths somade have i i been sold commercially and have been found to power of thecloth but does affect its saleability as many users prefer bags of, another color.

We have found thata cloth maybe impregnated with a silver compound which will protect silver enclosed in it from tarnish and that the cloth may other improvements inthe Grinnell Jones inven- 'We first dye our cloth in any suitable manner with any suitable fast color, the vat colors and naphthol colors being; preferred. Obviously no color should be used which-will be affected injuriously by the reagents. hereinafter described.

We take a suitable dyed 'napped cotton cloth, or plush, or similar suitable material, and pad. it with a solution containing 12 oz. of silver nitrate,

passed through the solution and then through 7 found best for this purpose thoughan Ot er suitable colloid may be used. This operation causes the prec pitation of the silver as silver ferrocyanide in accordance with the following reaction:

" algae. lus NarFemN) 6 precipitating tank, for instance, whatis called a jigger ;in which the clothi'mpregnated with j silver nitrate is lead from a roll through the bath under rollers and upto another roll.. It is then passed back again through the solution and soon,

back and forth,'until the silver ferrocyanide is.

properly precipitated, usually passing it back and Y forth six ends will be enough. The bath is then filled with water and the material iswashed in cold water by passing back and forth through the tank four,- to six ends until thoroughly freed from silver nitrate and prussiate of soda. The water in the padder and in the precipitating bath is preferably at room temperature.

By this means dyed cloth is impregn ated with V thewhite silver ferrocyanide 'which' scarcely affects the color of the cloth. If the cloth used is plush it will be desirable to use a kettle instead of a jigger for the precipitating bath and washing. 1 a

i We consider this cloth .an improvement on the disclosure of the Jones patent in the following particulars: r

(l) A cloth. of almost any color may be used, thus pleasing customers.

i (2) By reason of the user the colloid the silver is very finely precipitated so-that. more protection is obtainable from the same amount of silver- (31 By precipitating in a cool solution the silver is precipitated in a more finely divided form and gives better protection.

The percentage of silver used. may be ,varied considerably but it is not desirable to use too great a percentage of silver.. Less protection is obtained rather than more if a very large percentage of silverfis used. If too much silver is used, it is likely to be in a dense form which does '-not react so completely'with the sulphur gases. The best protection is obtained when the silver is spread through the material in a very finely divided'precipitate.

The expressions finely, divided precipitate and the like are used in this specification to mean a precipitate as fine as that obtainedrby the use of liquid atroom ing bath.

The fabric may; be used in any suitable way, as asbag,a lining for drawers or boxes. It will temperature in the precipitatgive partial protection even if placed loosely in a drawer with the silver. i

We claim:

1. A fabric for protecting silverware from tarnish comprising a material suitablefor wrapping, impregnated with silver ferrocyanide."

2. A fabric for protecting silverware from tarnish comprising a material suitable for wrap,

' 'nated fabric.

from V tarnish which consists in impregnating a-fabric with silver ferrocyanide and surrounding the silverware by said impregnated fabric.

5. The method of protecting silverware from tarnish which consists in impregnating a fabric with silver ferrocyanide precipitated in a solution containing an organic colloid so as to cause the silver ferrooyanide to be precipitated in a very finely divided form throughout the material and surrounding the silverware by said impreg- 6. 'A fabric for protecting silverware from tarnish comprising a material dyed with a suitable dyestufi and impregnated with silver ferrocy- .anide precipitated in the fabric in connection with an organic colloid. I

KENNETH H. .BARNARD.

" HENRY F. KANE. 

